Hot air or steam turbine power plant



April 12, 1960 J. HEGEMANN HOT AIR OR STEAM TURBINE POWER PLANT Filed Feb. 23, 1954 INVENTOR fa/7622222 J /eg'emazm BY ATTORNEY E l l l 2,932,169 nor AIR on STEAM TURBINE rowan PLANT Johann Hegemann, Ratingen, Rhineland, Germany, as-

signor to Durrenwerke Aktiengesellschaft, Ratingen,

This invention relates to a plant for supplying elastic working fluid at appropriate pressures and temperatures to high and low pressure turbines or turbine stages. In the operation of such a plant the working fluid must be reheated after it has performed Work in a high pressure turbineor turbine stage and before it flows to a low pressure turbine or turbine stage. In practice, reheating the working fluid introduces complications, particularly when the working pressure adopted calls for repeated reheating of the fluid. For example, if in a natural circulation boiler the steam is to be superheated and reheated and the final temperatures of superheat and reheat are to be maintained constant over as large a load range as possible, special constructional measures in connection with the superheater are required, such as the division of the superheater into radiation and convection sections or the provision of an adjustable by-pass. A forced flow boiler is able to give the desired superheat temperatureload characteristics without such constructional measures, but in all cases means must be provided for regulating the steam temperature at thev outlet of the reheater or re heaters.

An object of the invention is the provision of a plant adapted to heat and reheat elastic working fluid at respective pressures for use in different turbine stages or turbines and incorporating advantageous means for effecting regulation of the finaltemperature of the fluid at different pressures. V

The present invention includes means for supplying elastic working fluid at appropriate pressures and temperatures to high and low pressure turbines or turbine stages, including high or low pressure heaters connected in series respectively with opposite sides of a heat exchanger adapted by exchanging heat between the fluid at high pressure and the fluid at low pressure substantially to equalize the final temperatures of the fluid at the two pressures.

The invention also includes means for supplying elastic working fluid at appropriate pressures and temperatures to high and low pressure turbines or turbine stages, including high and low pressure heaters of which one has radiant and the other convection heat exchange characteristics, wherein the heaters are connected in series respectively with opposite sides of a heat exchanger adapted by exchanging heat between the fluid at high pressure and the fluid at low pressure to maintain the final temperature of the'fluid at high pressure and the final temperature of the fluid at low pressure at substantially predetermined values.

The invention Will now be described, by way of example, -with reference to the accompanying diagrammatic drawing showing an air heater and a two-stage gas turbine associated therewith.

In 'the drawing, a compressor 1 is arranged to deliver air to the series connected sections 2 and 3 of a high pressure air heater formed of radiation heating surfaces lining the walls of a furnace chamber. The outlet from the section 3 is connected through a valve 4 to a high pressure stage 5 of a gas turbine and between the outlet of the stage 5 and the inlet of a low pressure stage 8 of the turbine is connected a low pressure heater or reheater comprising series connected sections 6 and 7 formed of convection heating surfaces disposed in a gas pass leading from the furnace chamber. Between the sections 2 and 3 of the high pressure air heater is connected one side of a heat exchanger 9 and between the sections 6 and 7 of the low pressure air heater is connected the other side of the heat exchanger. The heat exchanger is so arranged in relation to the heaters that, at a certain intermediate load, the temperature of the air entering the heat exchanger from the heater section 2 is equal to the temperature of the air entering the heat exchanger from the heater section 6 and no heat exchange takes place.

In operation, the air supplied by the compressor 1 is heated in section 2 of the high pressure air heater'by the furnace gases and at the increased temperature enters the heat exchanger 9 and after leaving the heat exchanger is further heated in section 3 of the high pressure air heater to a final temperature at which the air enters the high pressure turbine stage 5. Having performed work in the turbine stage 5, the air flows at reduced temperature to section 6 of the reheater in which the air is heated before entering the heat exchanger 9. The air, upon leaving the heat exchanger 9, passes through section 7 of the reheater in which the air is heated to the final temper-- ature of reheat at which it enters the low pressure turbine stage 8 to perform further Work in that stage.

The high pressure heater, being predominantly radiantly heated, has a drooping load-temperature characteristic, while the reheater, being predominantly convectively heated, has a rising load-temperature characteristic. The heat exchanger 9 by efiiecting heat exchange between the high pressure air and the low pressure air tends to give flat load-temperature characteristics over a Wide load range.

Thus, as previously mentioned, at a certain intermediate load the respective inlet temperatures to the heat exchanger on the high and low pressure sides are equal and no heat exchange takes place. 'If the load increases above the said value the temperature of the air at the outlet from section 2 of the high pressure heater is reduced,

but the air temperature at the outlet of section 6 of the rei heater is increased. Consequently the increase of load is accompanied by an exchange of heat in the heat exchanger 9 whereby excess heat of the air at low pressure is transferred to the air at high pressure and tends to compensate for the deficiency of heat in the air at high pressure.

If, on the other hand, the load decreases below the said value, the process is reversed, excess heat of the air at high pressure being transferred to the air at low pressure and thereby tending to compensate for the deficiency of heat in the air at low pressure.

If desired, provision may be made for adjustably bypassing heating gases in relation to surfaces of the low pressure heater arranged to heat the working fluid flowing to the heat exchanger. Thus in the drawing is shown a gas by-pass 10 provided with a control damper 11 and arranged in parallel with the gas flow path containing the section 6 of reheater. By use of the by-pass, the load range over which the air temperatures at the inlets to the high and low pressure stages of the turbines may be controlled is increased and the possibility of influencing those temperatures is given.

While in accordance with the provisions of the statutes, there is illustrated and described herein specific forms of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

3 I claim: 1. In a power plant having a high pressure elastic fluid turbine and a low pressure elastic fluid turbine, at source predominantly heated by convection from the same gases,

a heat exchanger having one fluid side in indirect heat exchange relationship with a second side; means serially connecting the high pressure heatenone side of the heat exchanger, said high pressure turbine, said low pressure heater, the second side of the heat exchanger and the low pressure turbine, respectively, to provide an apparatus which combines in the high pressure and low pressure elastic fluid the heating effects of radiant and convection heating.

2. In a power plant having a high pressure elastic fluid turbine and a low pressure elastic fluid turbine, a source of high temperature flowing gases, a high pressure elastic fluid heater receiving heat from said gases, a low pressure elastic fluid heater receiving heat from the same gases, said high pressure heater being predominantly heated by radiation from said gases and the low pressure heater being predominantly heated by convection from the same gases, a heat exchanger having one fluid side in indirect heat exchange relationship with a second side; means serially connecting the high pressure heater, one side of the heat exchanger, said high pressure turbine, said low pres,- sure heater, the second side of the heat exchanger and the lowpressure turbine, respectively, to provide an apparatus which combines in the high pressure and low pressure elastic fluid the heating effects of radiant and convection heating.

3. In a power plant having a high pressure elastic fluid turbine and a low pressure elastic fluid turbine, a source of high temperature flowing gases, a high pressure elastic fluid heater receiving heat from said gases, a low pressure elastic fluid heater receiving heat from the same gases, said high pressure heater being predominantly heated by radiation from said gases and the low pressure heater being predominantly heated by convection from the same gases, a heat exchanger having one fluid side in indirect heat exchange relationship with a second side; means serially connecting the high pressure heater, one side of the heat exchanger, said high pressure turbine, said low pressure heater, the second side of the heat exchanger and the low pressure turbine, respectively, to provide an apparatus which combines in the high pressure and low pressure elastic fluid the heating eflects of radiant and convection heating, and a gas by-pass for adjustably bypassing gases around said convection heated low pressure heater.

4. In a power plant having a high pressure elastic fluid turbineand a low pressure elastic fluid turbine, a source of high temperature flowing gases, at high pressure elastic fluid heater having two serially connected sections receiving heat from said gases, at low pressure elastic fluid heater having two serially connected sections receiving heat from the same gases, said high pressure heater being predominantly heated by radiation from said gases and the low pressure heater being predominantly heated by convection from the same gases, a heat exchanger having one fluid side in indirect heat exchange relationship with a second side; means serially connecting one section of said high pressure heater, one side of said heat exchanger, the second section of the high pressure heater, said high pressure turbine, one section of said low pressure heater, the second side of said heat exchanger, the second section of said low pressure heater, and said low pressure turbine, respectively, to provide an apparatus which combines in the high and low pressure elastic fluid the heating efiects of radiant and convection heating.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain July 26, 1928 Switzerland Oct. 1. 1940 UNITED STATES PATENT OFFICE CER'IIFICATE 0F CORRECTION Patent No. 2,932 l69 April 12; 1960 Q Johann Hegemann g It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

' In the grant lines 2 and 12 and in the, heading to the printed specification line 4, name of assignee for "Durrenwerke' AktiengesellschaftFr each occurrence read Durrwerke Aktiengesellschaft column 3 line l4 for "heat exchanger" read heater Signed and sealed this 13th day of September 196,0.

(SEAL) Attest:

KARL AXLINE" ROBERT c. WATSON Attesting Officer T I Conmissioner of Patents 

